Ethan Lanphere is a student at Cornell University and the oldest of three boys. Three months ago, their father was no longer in the picture.

Ethan Lanphere

Since then, Ethan told BuzzFeed News he has been trying to step up to the plate as much as he can. He lives about two hours away from school, so it's been a challenge.

"It's been kind of hard to watch over everybody," he said.

His mom, Heather Lanphere, told BuzzFeed News that her job as an OB/GYN means that she works long hours, and so her sons have to watch over each other often.

"My boys have always been good at looking out for each other," she said.

This Father's Day, Heather said that she tried to prepare her youngest son, 9-year-old Jackson, to be without his dad. She told him that his class might make crafts and gifts for their dads, but he shouldn't feel pressured to participate.

Ethan Lanphere

She also told him that his teacher would understand if he decided to do something else instead while his class was preparing for the holiday.

"I put the seed in his head that it was coming up," she said.

Both Ethan and his mom said they were kind of dreading the holiday.

"It was a sad day," Ethan said. "It was the first day in god knows how long that I didn't have a father to celebrate."

Heather added that the day was especially painful because she also lost her own father, whom she shared her medical practice with, less than two years ago.

"I was not looking forward to Father's Day at all," she said. "I was very nervous about it."

However, Jackson had a different idea. He decided to write a card to Ethan instead, because he has become the father figure in his life.

Ethan Lanphere

Ethan Lanphere

"Dear Ethan, You are the person that I look up to. You have been my influence to make me a good person. Love, Jackson. PS: I love you," he wrote.

Ethan and his mom said neither of them knew Jackson had made the card, and he came up with it all on his own. When Jackson presented the card to Ethan on Father's Day, Ethan said it was hard not to cry.

"It put a huge smile on my face," he said.

His mom said the card made it a happy day, not a sad one.

"It's funny how it turned into such a great event that could make us all smile," she said. "It's all about being thankful for what you have, not what you don't have or what you've lost."

Ethan was so proud of his card, he decided to share it on Twitter. It really touched people's hearts.